US3595660A - Method of producing photographic images by physical developing utilizing diazosulfonates - Google Patents

Abstract

BENZENEDIAZOSULFONATES HAVING DISOCIATION CONSTANTS AT A PH OF 7.8 OF NOT GREATER THAN 5X10-7 AND MOLECULAR EXTINCTION COEFFICIENTS AT 435 NM. OF AT LEAST 1000 EMPLOYED IN LIGHT SENSITIVE LAYERS USED IN THE PRODUCTION OF PHOTOGRAPHIC IMAGES BY THE PHYSICAL DEVELOPEMENT OF A LATENT MERCURY METAL IMAGE.

Description

July 27, 1971 VAN BEEK ETAL 3,595,660

METHOD OF PRODUCING PHOTOGRAPHIC IMAGES BY PHYSICAL DEVELOPING UTILIZING DIAZOSULFONATES Filed Feb. 27, 1968 Z90 2 50 I 390 3 50 490 59D SP0 I I I I I I I I I I I I I -IIIvII-nII-In-IHHH-n Log E 10 -}L[cm"'] 1.00 I W N= N-SO Na w I5 5 ai-F259; Y HENDRIK JONKER AENT United States Patent Filed Feb. 27, 1968, Ser. No. 708,593 Claims priority, application Netherlands, Feb. 28, 1967, 6703133 Int. Cl. G03c 1/56, 1/62, 5/34 US. CI. 9649 8 Claims ABSTRACT OF THE DISCLOSURE Benzenediazosulfonates having dissociation constants at a pH of 7.8 of not greater than 5X10 and molecular extinction coefiicients at 435 nm. of at least 1000 employed in light sensitive layers used in the production of photographic images by the physical development of a latent mercury metal image.

The invention relates to a method of producing photographic images With the aid of a light-sensitive material consisting of a basic layer which at the surface at least is not electrically conductive and on or in which surface where the light-sensitive layer proper is provided, contains an aromatic diazosulphonate.

The light-sensitive layer may be obtained by saponifying a surface layer of a cellulose-ester foil or by anodic oxidation of an aluminum foil and subsequent impregnation of the hydrophilic layer with a solution containing a diazosulphonate. The layer may also contain a hydrophilic base, for example, paper or cellophane. The material may furthermore consist of a basic layer of a material which cannot be impregnated with water and on which a vitreous, light-sensitive layer is provided by means of a predominantly aqueous solution containing the aromatic diazosulphonate and, if necessary, a wetting agent and/or one or more further compounds for preventing crystalline drying of the layer.

Such light-sensitive material is employed in a known method producing photographic pictures, in which the diazosulphonate dissociates by the effect of the light at least partly via a labile isomeric form into a light-reaction product consisting of a diazoniumdon and a sulphite ion. When the exposed layer is brought into contact with an aqueous solution containing mercurous ions and preferably also silver ions, a latent image is formed which consists of physically developable metal nuclei, the formation of which is due to the sulphite ions. By physical development this latent image is intensified into a visible metal picture.

A factor of essential importance in the question whether a given diazosulphonate can be used for the production of pictures in the above-system is the dissociation constant in the dark of the equation:

If the diazosulphonate has dissociated too much already in darkness, the reaction in which metal nuclei are deposited will take place also at the unexposed areas of the material which results in the formation of fog. It has been found experimentally that in suitable light-sensitive layer in which for example a film of cellulose-triacetate, saponified superficially to a depth of 6 is sensitized by impregnating it in a solution containing 0.1 mol/litre of diazosulphonate the dissociation constant in the dark of the diazosulphonate employed, determined in an aqueous solution of pH 7.8 must not exceed a value 5X10? Material containing a light-sensitive compound satisfying this condition will not exhibit unwanted fogging, when the metal nuclear image is suitably formed and intensified.

A disadvantage of the known compounds suitable for the aforesaid photographic purposes, for example the sodium salt of 0- or p-methoxy benzene diazosulphonic acid, resides in that the spectral absorption only very slightly extends into the visible Wave range (about 400 nm.). For this reason, when using the known physical method of development for example for magnification, for instance of microfilm pictures, it is necessary to employ special light sources (mercury vapor discharge lamps) and to use optical systems which have a good transmittance for radiation of the wave-range between 300 and 400 nm. and which permit a reasonable correction for said radiation. Such optical systems are very difiicult to obtain commercially.

The same problem exists in the use of said methods for the manufacture of photomasks for integrated circuits, for which purpose these methods are extremely suitable owing to the high resolving power and the excellent sharpness of the edges. The commercially available step and repeat cameras cannot be employed for this purpose.

In diazotypes a number of substituted diazosulphonates sensitive to light of longer wavelengths are known, it is true (the Peer-process), but in such cases the abovementioned dissociation constants in the dark are too high for the instant photographic system, so that fogging results. In a diazotype method, in which no intensifying mechanism is involved, this dark equilibrium does not play an important role.

According to the invention there is provided a class of diazosulphonates suitable for the instant photographic system which have dissociation constants in the dark reaction of less than 5 X10 and molecular extinction coefiicients at 435 nm. of at least 1000.

The method according to the invention for the manufacture of photographic pictures is characterized in that use is made of an aromatic diazosulphonate which satisfies the following general formula Y2 Zz X N=N-SO'3 Me YL1 J11 11 in which X is an electron-repelling group formed by:

morpholino, piperidino, piperazino, wherein R and R are hydrogen, alkyl, phenyl or cyclohexyl groups, X being chosen so that the diazosulphonate has a molecular extinction coefficient at 435 nm. of at least 1000, Y and Y being hydrogen, halogen, NO CN, -CF

or -O R, while R is an alkyl-group, phenyl-group or a cyclohexyl-group, Z and Z being hydrogen or halogen and Me is a mono or divalent metal cation, n has avalue of l or 2, while of the groups Y Y Z and Z at the most three are hydrogen and, if Y and/or Y is not hydrogen, Z and/or Z may be an alkyl-group.

In order to improve the solubility of the diazosulfonate sulphonic acid groups or salts thereof may be provided at free positions in the molecule. It is advantageous if in the aforesaid formula the substituent R in X and/or in Y and Y designates an alkyl-group having more than 8 carbon atoms. The use of such long chain groups diminishes the diffusion of the light-sensitive compound. When the sensitized layer is dried, substance transfer may occur, so that an unhomogeneous light-sensitive material is obtained. By introducing these long chains as substituents this risk is considerably reduced.

A preferred class of the benzenediazosulfonates that may be employed in our invention are those of the above formula wherein X is a moiety selected from the group consisting of diethylamino, dimethylamino, methylamino and morpholino, Y is selected from the group consisting of hydrogen and chlorine, Y is selected from the group consisting of hydrogen, chlorine, bromine, nitro and carboxy, Z is selected from the group consisting of hydrogen, chlorine and methoxy and Z is selected from the group consisting of hydrogen, fluorine, chlorine and methyl.

After the termination of the light reaction the diazosulphonate tends to regress, as is known, from the light reaction product to the diazosulfonate molecule so that the physical developability of the layer will disappear gradually and tends to become more prevalent as the period of time between the termination of the exposure and the contact with the solution containing mercurous ions increases. This phenomenon is known as the regression of the result of exposure and it is combatted effectively by providing in the light-sensitive layer, in addition, a compound, called an anti-regression agent, which prevents diazosulphonate from being reformed from its lightreaction product, by binding either the sulphite ion or the diazonium ion or both so that the sulphite remains capable of reacting with the mercurous salt While forming mercury nuclei. The most elfective anti-regression agents are the Water-soluble salts having cations which form with sulphite ions poorly soluble or slightly dissociated sulphites, such as Zn++, Cd++, Pb++, Cu++ and Na These cations may also be employed in the form of salts of the light-sensitive diazosulphonic acids.

In a preferred form of the method according to the invention the known anti-regression agents are also employed. The effect of the sensitivity to visible radiation may in some cases be surprisingly intensified by adding an anti-regression agent. Examples of such anti-regression agents are disclosed in US. Pat. 2,838,398.

In a particularly preferred form, the light-sensitive layer contains, apart from a suitable diszosulphonate, a soluble silver salt as an anti-regression agent in conjunction with a soluble mercurous salt. Owing to the presence of the mercurous compound, to some extent dependent upon the degree of humidity of the light-sensitive material, partial formation of the image consisting of nuclei may take place directly during the exposure. The presence of the mercurous compound is, moreover, conducive to the preservability of the light-sensitive material, also owing to the mercuric ions in the equilibrium; the use of a silver compound alone would be harmful to said preservability. Conversely, the presence of the silver compounds furthers the stability of the formed image consisting of nuclei. It has been found, however, that the diazosulphonates according to the invention, if they have a group X=NR R -used in the layer together with for example, mercurous nitrate-tend to fogging, which is probably due to the reaction of mercurous ions with the amino-group. However, if diazosulphonates containing a group X consisting of morpholino or piperidino are used in the layer together with a mercurousand a silver-salt, the advantages of this method: a very slight regression of the result of exposure and an excellent resolving power may be obtained.

As a rule, a base layer which is hydrophilic at least at the surface can be sensitized in a simple manner by impregnating it with an aqueous solution containing the diazosulphonate and, if necessary, auxiliary substances. If, however, one or more of these compounds are not adequately soluble in water, they may be introduced into the layer by indirect means by impregnating them with water and subsequently replacing the water by dissolving the diazosulphonate and auxiliary substances, if any, in a solvent which is miscible with water.

The invention will be described more fully hereinafter with reference to a few examples and to a drawing, the sole figure is a graph of molecular extinction of the diazosulfonates versus wavelength of the exciting radiation.

EXAMPLE 1 Strips of cellulose triacetate foil saponified to a depth of 2 m. were sensitized on one surface by impregnating them for 2 minutes and 24 C. in aqueous solutions containing, apart from 10 drops of 50% by weight of Lissapol N as a wetting agent, per litre:

(a) 0.10 mol of the sodium salt of 3,5-dichloro-4-dimethylamino-benzene-diazosulphonic acid (molecular extinction at 435 nm. =4370, dissociation constant at 25 C. and pH=7.8 is 2.4 10 and 0.10 mol of cadmium lactate as an anti-regression agent;

(b) 0.10 mol of sodium salt of p-methoxy-benzene-diazosulphonic acid (molecular extinction at 435 nn1.=363, dissociation constant at 25 C. and pH=7.8 is 6.6 10- and 0.10 mol of cadmium lactate. Strips of a cellulose triacetate foil, saponified to a depth of 6 were sensitized by impregnating them for 2 minutes and at 25 C. in aqueous solutions, containing per litre;

(c) 0.20 mol of sodium salt of 3.5-dichloro-4-dimethylamino-benzene-diazosulphonic acid and 10 drops of 50% by weight of Lissapol N;

(d) 0.20 mol of sodium salt of 4-dimethylamino-benzene-diazosulphonic acid (molecular extinction at 435 nm.=25,200, dissociation constant at 25 C. and pH=7.8 is 2.9 1O" and 10 drops of 50% by weight of Lissapol N.

After the removal of the adhering liquid by wiping it off between the .two rubber strips, the film strips were dried in a fiow of hot air and then kept for about 12 hours in a space through which there was passed air of 50% of relative humidity.

Lengths of the strips (21) and (b) were exposed by means of a sensitometer to light of a longer wavelength than 420 nm., obtained from a combination of a highpressure mercury-vapor discharge lamp (250 w.) and a G.G.3-filter (Jenaer Glaswerk Schoot and Gen.). The exposed strips were treated immediately after exposure for 4 seconds with a solution of 0.005 mol mercurous nitrate and 0.01 mol of silver nitrate and 0.01 mol of nitric acid in distilled water in order to form an image. Then the strips were rinsed in distilled water for 10 seconds and then physically developed at 25 for 4 minutes by means of a solution containing per litre:

0.05 mol of ferrous ammonium sulphate, 0.01 mol of ferric nitrate,

0.10 mol of citric acid,

0.01 mol of silver nitrate,

0.02% by weight of Armac 12D, 0.02% by weight of Lissapol N.

(Armac 12D) is a cationic surface-active substance consisting for about of dodecylaminoacetate, for about 9% of tetradecylamino-acetate and otherwise of higher alkylaminoacetates. Lissapol N is a non-ionic surface-active substance consisting of a condensation product of ethylene oxide with alkyl phenols.

Unexposed lengths of the strips (c) and (d) were treated for 4 seconds with the above-mentioned solution of mercurous ions, rinsed for 10 seconds in distilled water and then physically developed for 14 minutes at 25 C. in the aforesaid developer. Subsequent to rinsing and drying, the density of the film strips were measured. From the completely fog-free density wedges on the film strips (a) and (b) it appeared that the threshold sensitivity in the case (a) was at least a factor 5 higher than in the case (b). In the case (c) a density of 0.03 and in the case (d) a density of 0.20 were measured. The absorption spectra of the three compounds employed are indicated in the drawing the sole figure of which is a graph wherein a log of the molecular extinction (Log 6) is plotted against the wavelength (upper abscissa) nm., and wave number (lower abscissa) of the exciting radiation of the diazosulfonates employed in this example.

EXAMPLE 2 Strips of a cellulose triacetate foil, saponified to a depth of 2 m., were sensitized on one side by impregnating them for 2 minutes at 25 C. in aqueous solutions, containing per litre:

(a) 0.10 mol of sodium salt of 3-chloro-4-morpholinobenzene-diazosulphonic acid (molecular extinction at 435 nm.:2040, dissociation constant at 25 and pH 7.8 is 1.1 1.() and drops of 50% by weight of Lissapol N,

(b) 0.10 mol of sodium salt of 2-fluoro-4-dirnethylamino-benzene-diazosulphonic acid (molecular extinction at 435 nm;=26,900, dissociation constant at C. and pH=7.8 is 80x10) and 10 drops of 50% by weight of Lissapol N.

(c) 0.10 mol of sodium salt of 2-chloro-4-dimethylamino benzene diazosulphonic acid (molecular extinction at 435 nm.=24,550, dissociation constant at 25 and pH=7.8 is 1.0 10= and 10 drops of 50% by weight of Lissapol N.

(d) 0.10 mol of sodium salt of p-methoxy-benzenediazosulphonic acid and 10 drops of 50% by weight of Lissapol N.

After the removal of the adhering liquid by wiping it off between two rubber strips the film strips were dried in a flow of hot air and then kept overnight in a space conditioned at 50% of relative humidity. Lengths of these strips were exposed by means of a sensitometer to light of longer wavelengths than 420 nm., obtained from the combination of a high-pressure mercury vapor discharge lamp (250 w.) and a G.G.3-filter (Jenaer Glaswerk Schott and Gen).

The exposed strips were treated directly after exposure for 4 seconds with the mercurous ions containing solution of Example 1. The strips were then rinsed for 10 seconds in distilled water and then physically developed for 4 minutes at 25 C. in the developer of Example 1.

After rinsing and drying the fog-free density wedges on the film strips were measured by means of a densitometer. The threshold sensitivity of strips (a), (b) and (c) was a factor 3 higher than that of the strip ((1).

EXAMPLE 3 Strips of a cellulose triacetate foil, saponified to a depth of 2 m., were unilaterally sensitized by impregnating them on one side for 2 minutes at 25 C. in aqueous solutions containing, apart from 0.10 mol of cadmium lactate and 10 drops of 50% by weight of Lissapol N, per litre:

(a) 0.10 mol of sodium salt of 3-fiuoro-4-dimethylamino benzene diazosulphonic acid (molecular extinction at 435 nm.=9550 dissociation constant at 25 C. and pH=7.8 is 3.4 10- (b) 0.10 mol of sodium salt of 3-chloro-4-dimethylamino benzene diazosulphonic acid (molecular extinction at 435 nm.=4000, dissociation constant at 25 C. and pH=7.8 is 1.8 10* (c) 0.10 mol of sodium salt of 3-bromo-4-dimethylamino-benzene-diazosulphonic acid (molecular extinction at 435 nm.:3090 dissociation constant at 25 C. and pH=7.8 is 1.5 10

(d) 0.10 mol of sodium salt of 3-chloro-4-diethylamino-benzene-diazosulphonic acid (molecular extinction at 435 nm.:4550, dissociation constant at 25 C. and pH=7.8 is 2.1 10

(e) 0.10 mol of sodium salt of p-methoxy-benzene diazosulphonic acid. After the removal of the adhering liquid by wiping it off between two rubber strips the films were dried in a flow of hot air and then conditioned for 12 hours at 50% of relative humidity.

Lengths of these strips were exposed for 2 minutes to light of a wavelength of 435 nm. (band width 10 nm.), obtained from a combination of a Bausch and Lomb monochromator (light source high-pressure mercuryvapor discharge lamp HP and a G.G.-3-filter (Jenaer Glaswerk Schott and Gen).

The distance between the film strip and the outlet gap of the monochromator was 7.5 ems. The exposed strips were treated immediately after the exposure for 4 seconds with the solution of mercurous ions of Example 1. Then the strips were rinsed in distilled water for 10 econds and then physically developed at 25 C. for 4 minutes in the developer of Example 1. After rinsing and drying the density of the exposed areas was measured the results being as follows:

film strip (a): density D=1.3 film strip (b): density D=1.0 film strip(c): density D=1.1 film strip (d): density D=0.50

The unexposed areas of the strips were quite free of fogging. Film strip 0 has no density at all.

EXAMPLE 4 Strips of a cellulose triacetate foil, aponified to a depth of 2 m, were unilaterally sensitized on one side by impregnating them for 2 minutes at 25 C. in aqueous solutions containing, apart from 10 drops of 50% by weight of Lissapol N, per litre:

(a) 0.10 eq. of cadmium salt of 3-carboxy-4-dimeth ylamino-benzene-diazosulphonic acid (molecular extinction at 435 nm.=10,470, dissociation constant at 25 C. and pH=7.8 is 24x10);

(b) 0.10 mol of sodium salt of 2-methyl-4-dimethylamino 5 chloro benzene diazosulphonic acid (molecular extinction at 435 nm.:3160, dissociation constant at 25 C. and pH=7.8 is 9.O 10* and 0.10 mol of cadmium lactate as an anti-regression agent;

(0) 0.10 mol of sodium salt of 2-chloro-4-dimethylamino 5 methoxy benzene diazosulphonic acid (molecular extinction at 435 nm. =6030, dissociation constant at 25 C. and pH=7.8 is 3.2 10" and 0.10 mol of cadmium lactate,

(d) 0.10 mol of sodium salt of 3.5-dichloro 4 methylamino benzene diazosulphonic acid (molecular extinction at 435 nm.:6200, dissociation constant at 25 C. and pH:7.8=1.0 1O- and 0.10 mol of cadmium lactate,

(e) 0.10 mol of sodium salt of p-methoxy-benzene-diazosulphonic acid and 0.10 mol of cadmium lactate.

After the removal of the adhering liquid by wiping it oif between two rubber strips the film strips were dried in a flow of hot air and then kept for about 12 hours in a space having a relative humidity of 50%. Lengths of these strips were exposed by means of a sensitometer to light of a longer wavelength than 420 nm., obtained from the combination of a high-pressure mercury-vapor discharge lamp (250 w.) and a G.G.-3- filter (Jenaer Glaswerk Schott and Gen). Immediately after exposure the strips were treated for 4 seconds with the solution containing mercurous ions of Example 1. Then they were rinsed in distilled water for 10 seconds and then physically developed for 4 minutes at 25 C. in the developer of Example 1. After rinsing and drying the quite fogfree density wedges on the film strips were measured by means of a densitometer. The threshold Sensitivity of the strips (a), (b), (c) and (d) is a factor, 2, 3, 2 and 3 respectively higher than that of the strip (e).

7 EXAMPLE Sheets of basic paper for diazotypics were sensitized on one side by aqueous solutions containing, apart from drops of 50% by weight of Lissapol N, per litre:

(a) 0.20 mol of sodium salt of 3 bromo-4-dimethylamino-benzene-diazosulphonic acid and 0.10 mol of cadmium lactate as an anti-regression agent,

(b) 0.20 mol of sodium salt of p-methoxy-benzenediazosulphonic acid and 0.10 mol of cadmium lactate.

After drying in air each of these sheets was provided With an 8-fold magnification of a micro-negative with the aid of a commercially available slide projector. After exposure the sheets were treated for 4 seconds with a solution containing 0.005 mol of mercurous nitrate and 0.001 mol of silver nitrate and 0.01 mol of nitric acid in distilled Water. The sheets were then rinsed for 10 seconds in distilled Water and subsequently physically developed for 2.5 minutes at room temperature in the developer of Example 1. Finally the magnifications were rinsed again and fixed in 0.10 mol of sodium thiosulphate for at least 1 minute, after which the sheets were again rinsed in water. The exposure time in the case (a) could be chosen a factor 2 shorter than in the case (b).

EXAMPLE 6 Strips of a cellulose-triacetate foil, saponified to a depth of 2 ,um, were sensitized by impregnating them for 2 minutes in aqueous solutions at room temperature, containing apart from a small quantity of Lissapol N as a wetting agent, per litre:

(a) 0.10 eq. of sodium salt of 3-chloro-4-morpholinobenzene diazosulphonic acid, 0.10 mol of cadmium lactate, 0.01 eq. of mercurous nitrate, and 0.01 eq. of silver nitrate;

(b) 0.10 eq. of sodium salt of p-methoxy-benzene-diazosulphonic acid, 0.10 mol of cadmium lactate, 0.10 eq. of mercurous nitrate and 0.01 eq. of silver nitrate.

After the removal of the adhering liquid by wiping it off between two rubber strips the film strips were dried in a flow of hot air and then kept overnight in a space having a relative humidity of 50%. Lengths of these strips were exposed by means of a sensitometer to light of a longer wavelength than 400 nm., produced by the combination of a high-pressure mercury-vapor discharge lamp (250 w.) and a G.G.4-filter (Jenaer Glaswerk Schott and Gen.). The exposed strips were treated with the mercurous solution of Example 1. Then the strips were rinsed in distilled water for 10 seconds and subsequently physically developed for 4 minutes at C.

in the developer of Example 1. After rinsing and drying the fog-free density wedges on the -film strips were measured by means of a densitometer. The threshold sensitivity of strip (a) was a factor 3 higher than that of the strip (b).

EXAMPLE 7 Strips of a cellulose-triacetate foil, saponified to a depth of 2 ,um. were sensitized on one side by impregnating them for 2 minutes in distilled water and then for 3 minutes, immediately after the removal of the adhering liquid by wiping it off between two rubber strips, in alcoholic solutions at room temperature, containing per litre:

(a) 0.10 mol of cadmium salt of 2,5-dichloro-4-dimethylamino-benzene-diazosulphonic acid in ethanol (molecular extinction at 435 nm.=5120, dissociation constant at C. and pH=7.8 is 1.4 10- (b) 0.10 mol of cadmium salt of p-methoxy-benzenediazosulph'onic acid in methanol.

After the removal of the adhering liquid by wiping it off between two rubber strips the film strips were dried in a flow of hot air and then kept overnight in a space having a relative humidity of 50%. Lengths of these strips were exposed by means of a sensitometer to light of a longer wavelength than 400 nm. produced by the combination of a high-pressure mercury vapor discharge lamp (250 w.) and a G.G.4-filter (Jenaer Glaswerk Schott and Gen.). After the exposure the film strips were treated for 4 seconds with the mercurous solution of Example 1. Then the strips were rinsed in distilled water for 10 seconds and then physically developed for 4 min utes at 25 C. in the developer of Example 1. After rinsing and drying the completely fog-free density wedges on the film strips were measured by a densitometer.

The threshold sensitivity of the strip (a) is a factor 6 higher than that of the strip (b).

EXAMPLE 8 Strips of a cellulose-triacetate foil, saponified to a depth of 2 ,um. were sensitized on one side by impregnating them at 25 C. for 2 minutes in aqueous solutions containing, apart from 10 drops of by weight of Lissapol N as a wetting agent, per litre:

(a) 0.02 mol of cadmium salt of 3-nitro-4-dimethylamino-benzene-diazosulphonic acid (molecular extinction at 435 nm.:6400, dissociation constant at 25 C. (and pH:7.8 is 8.0 10- (b) 0.02 mol of cadmium salt of p-methoxy-benzenediazosulphonic acid.

After the removal of the adhering liquid by wiping it off between two rubber strips the film strips were dried in a 'flow of hot air and then kept for about 12 hours in a space traversed by air of 50% of relative humidity.

Lengths of the strips (a) and (b) were exposed by means of a sensitometer to light of a longer wavelength than 400 nm., produced by the combination of a highpressure mercury vapor discharge lamp (250 v.) and a G.G.4-filter (Jenaer Glaswerk Schott and Gen.). The exposed strips were treated for 4 seconds with a mercurous solution of Example 1.

Then the strips were rinsed for 10 seconds in distilled water and then physically developed for 4 minutes at 25 C. in the developer of Example 1. After rinsing and drying the completely fog-free density wedges 0n the film strips were measured by means of a densitometer. The threshold sensitivity of the strip (a) is at least a factor 3 higher than that of the strip (b).

The following sodium salts of the sulphonic acids are examples of the light-sensitive diazosulfonates according to the invention:

3,5-dichloro-4-dimethylaminobenzenediazosulphonic acid 3-chloro-4-morpholinobenzenediazosulphonic acid Z-fluoro-4-dimethylaminobenzenediazosulphonic acid 2-chloro-4-dimethylaminobenzenediazosulphonic acid 3-fluoro-4-dimethylamjnobenzenediazosulphonic acid 3-chloro-4-dimethylaminobenzenediazosulphonic acid 3-bromo-4-dimethylaminobenzenediazosulphonic acid 3-ohl0ro-4-diethylaminobenzenediazosulphonic acid 3-carboxy-4-dimethylaminobenzenediazosulphonic acid 2-methyl-4-dimethylamino-5-chlorobenzenediazosulphonic acid 2-chloro-4-dimethylamino-S-methoxybenzenediazosulphonic acid 3,S-dichloro-4-methylaminobenzenediazosulphonic acid 2,S-dichloro-4-dimethylaminobenzenediazosulphonic acid 3-nitro-4-dimethylaminobenzenediazosulphonic acid 3-chloro-4-piperidinobenzenediazosulphonic acid 3-chloro-4-diphenylaminobenzenediazosulphonic acid 3-chloro-4-dicyclohexylaminobenzenediazosulphonic acid 3-chloro-4-aminobenzenediazosulphonic acid 3-cyano-4-dimethylaminobenzenediazosulphonic acid 3-trifluoromethyl-4-dimethylaminobenzenediazosulphonic acid 3-carbonamido-4-dimethylaminobenzenediazosulphonic acid 3-phenylcarbonyl-4-dimethylaminobenzenediazosulphonic acid 3carboethoxy-4-dimethylaminobenzencdiazosulphonic acid 3-carbophenoxy-4dimethylaminobenzenediazosulphonic acid 3-benzoylamino-4-dimethylaminobenzenediazosulphonic acid 3-acetyl-4-dimethylaminobenzenediazosulphonic acid 3,5-diacetyl-4-d-iethylaminobenzenediazosulphonic acid 3-cyclohexylcarbonyl-4-dimethylaminobenzenediazosulphonic acid S-hexahydrobenzoylamino-4-dimethylaminobenzenediazosulphonic acid 3acetylamino-4-dimethylaminobenzenediazosulphonic acid 3stearylamino-4-dimethylaminobenzenediazosulphonic acid 3,S-distearylamino4-dimethylaminobenzenediazosulphonic acid 2,5-dichloro-4-dilaurylaminobenzenediazosulphonic acid 2,6-dichloro4-dimethylarninobenzenediazosulphonic acid 2,6-diethyl-4-dimethylamino 5chlorobenzenediazosulphonic acid 2-ohloro-6isobutyl-4-dimethylaminobenzenediazosulphonic acid 2,3,5trichloro-4-an1inobenzenediazosulphonic acid 2,3,6-trichloro-4-aminobenzenediazosulphonic acid 3,S-dicyclohexylcarbonyl-4-dimethylaminobenzenediazosulphonic acid 3,5-dichloro-4-diphenylaminobenzenediazosulphonic acid 3-chloro-4-dicyclohexylaminobenzenediazosulphonic acid 3chloro-Scyclohexylcarbonyl-4-aminobenzenediazosulphonic acid 3-chloro-4-piperazinobenzenediazosulphonic acid.

While we have described our invention in connection with specific embodiments and applications, other modifications thereof will be readily apparent to those skilled in this art without departing from the spirit and scope of the invention as defined in the appended claims.

What we claim is:

1. In a method of producing photographic images by first either 1) selectively exposing to actinic light a supported light sensitive layer containing a water soluble mercurous compound and a light-sensitive diazosulfonate and (2) treating the exposed layer with water to form a latent metal image, or (1) selectively exposing to actinic light a light sensitive layer containing a light sensitive diazosulfonate and (2) treating the exposed layer with Water and a water-soluble mercurous salt to form a latent metal image; and then (3) physically developing the latent metal image by treatment with an aqueous solution of a metal salt and a reducing agent for the metal salt, the improvement which comprises employing as the lightsensitive diazosulfonate a compound of the formula I I Y; Z1 11 wherein X is an electrophobic moiety selected from the group consisting of morpholino, piperidino and wherein R and R are each selected from the group consisting of phenyl, cyclohexyl, hydrogen and alkyl, Y and R are each moieties selected from the group consisting of hydrogen, halogen, NO CN, CF;.,,

and OR wherein R is a member selected from the group consisting of alkyl, phenyl and cyclohexyl, Z and Z are each moieties selected from the group consisting of hydrogen, halogen and alkyl of 1 to 6 carbon atoms, Me is a metal cation, selected from the group consisting of Na+, Zn++, Cd++, Pb++ and Cu++, n is a whole number from 1 to 2 inclusive, With the proviso that at least one of the moieties Y Y Z and Z is other than hydrogen and one of the moieties Z and Z is alkyl only when one of the moieties Y and Y is other than hydrogen, said light sensitive diazosulfonate being further characterized in having a molecular extinction coeiiicient at 435 mm. of at least 1000 and a dissociation constant in the dark reaction of less than 5 1()- when determined in an aqueous solution of pH 7.8.

2. The method of claim 1 wherein the light-sensitive layer contains in addition an anti-regression agent capable of reacting with one or more of the light decomposition products of the diazosulfonate formed upon exposure to light and prevents formation of the diazosulfonate from these light decomposition products.

3. The method of claim -1 wherein the light sensitive layer contains a Water soluble mercurous compound and a water-soluble silver salt of the diazosulfonate and the electrophobic moiety X is selected from the group consisting of morpholino and piperidino.

4. The method of claim 1 wherein the exposed layer is treated with an aqueous solution containing silver ions and mercurous ions.

5. The method of claim 1 wherein the water soluble mercurous compound is present in the light sensitive layer.

6. The method of claim ll wherein at least one of the moieties designated by R, R and R is alkyl of more than eight carbon atoms.

7. A light sensitive material comprising a support the surface at least of which is electrically non-conductive said material having a light-sensitive layer thereon, said layer containing a water soluble mercurous salt and as a light-sensitive diazosulfonate a compound of the formula wherein X is an electrophobic moiety selected from the group consisting of morpholino, piperidino and wherein R and R are each selected from the group consisting of phenyl, cyclohexyl, hydrogen and alkyl, Y and Y are each moieties selected from the group consisting of hydrogen, halogen, NO CN, CF;,,

0 O O O 0 NH OH OR R H and OR wherein R is a member selected from the group consisting of alkyl, phenyl and cyclohexyl, Z and Z are each moieties selected from the group consisting of hydrogen, halogen and alkyl of 1 to 6 carbon atoms, Me is a metal cation, selected from the group consisting of Na+, Zn++, Cd++, Pb++ and Cu++, n is a whole number from 1 to 2 inclusive, with the proviso that at least one of the moieties Y and Z is alkyl only when one of the moieties Y and Y is other than hydrogen, said light sensitive diazosulfonate being further characterized in having a molecular extinction coefficient at 435 nm. of at 1 1 least 1000 and a dissociation constant in the dark reaction of less than 5 x10 when determined in an aqueous solution of pH 7.8.

8. The light sensitive layer of claim 7 wherein a water soluble silver salt is present in said layer and the moiety X is selected from the group consisting of morpholino and piperidino.

References Cited UNITED STATES PATENTS 2,618,555 11/1952 'Reichel 96-49 3,223,525 12/1965 Jonker et al. 96--49X 3,385,705 5/1968 Dippel et al. 9675 3,479,183 11/1969 iI-Iabib et a1. 96-49 OTHER REFERENCES Dinaburg, M. S., Photosensitive Diazo Cpds., 1964, pp. 213-220.

Kosar, 1., Light-Sensitive Systems, 1965, pp. 27227-6.

Landau et al., The Journal of Photo Sci, vol. 13, 1965, pp. 144-151.

NORMAN G. TORCHIN, Primary Examiner C. L. BOWERS, 1a., Assistant Examiner U.S. Cl. X.R. 96-75, 91

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